An Evidence Of Rapid Hydrogen Chloride Uptake On Water Ice In The Atmosphere Of Mars

By Keith Cowing
Status Report
December 12, 2023
Filed under , , ,
An Evidence Of Rapid Hydrogen Chloride Uptake On Water Ice In The Atmosphere Of Mars
An illustration of the anticorrelation between the HCl abundance and water ice from a single observation (Panels A, B, and C) and from all “HCl in ice-holes” cases (Panel D). Panel A. The aerosol extinction profiles at 3.09-3.46 μm (water ice band, yellow and red) and 0.76-1.6 μm (aerosol continuum, green and blue) measured by MIR and NIR, respectively. Panel B: Retrieved aerosol mass loading profiles of dust (red) and water ice (blue), bottom axes; temperature profile with uncertainties retrieved from NIR data (Fedorova et al., 2023), orange area and top axes. Panel C: volume mixing ratio of HCl (black lines and bottom axes) and H2O (blue lines and top axes) retrieved from MIR and NIR, respectively. Panel D: profiles of HCl VMR (black lines) and aerosol extinction at 3.1 μm (blue lines) normalized to [0, 1] and shifted to align all HCl maxima at 45 km; mean profiles are shown in bold. Error bars of the experimental data correspond to 1−σ uncertainty level. — astro-ph.EP

In 2020, hydrogen chloride (HCl) in the gas phase was discovered in the atmosphere of Mars with the Atmospheric Chemistry Suite (ACS) onboard the Trace Gas Orbiter (TGO) mission (Korablev et al., 2021).

Its volume mixing ratio (VMR) shows a seasonal increase of up to 5 ppbv during the perihelion season, followed by a sudden drop to undetectable levels, contradicting previous estimations of the HCl lifetime of several months. In the Earth’s stratosphere, heterogeneous uptake of HCl onto water ice is known to be a major sink for this species.

Modelling of associated chemistry involving heterogeneous reactions indicates that H2O ice becomes the most effective sink for HCl above 20 km with the characteristic time shorter than 12 hours. In this work, we use simultaneous measurements of water ice particles and HCl abundance obtained by the ACS instrument and show particular structures in the vertical profiles, forming detached layers of gas at the ice free altitudes (‘ice-holes’).

We demonstrate that the heterogeneous uptake of HCl onto water ice operates on Mars and is potentially a major mechanism regulating the HCl abundance in the atmosphere of Mars.

Mikhail Luginin, Alexander Trokhimovskiy, Benjamin Taysum, Anna A. Fedorova, Oleg Korablev, Kevin S. Olsen, Franck Montmessin, Franck Lefèvre

Comments: 7 pages, 1 figure. Submitted to Icarus Notes
Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Atmospheric and Oceanic Physics (
Cite as: arXiv:2312.07209 [astro-ph.EP] (or arXiv:2312.07209v1 [astro-ph.EP] for this version)
Submission history
From: Mikhail Luginin
[v1] Tue, 12 Dec 2023 12:21:11 UTC (492 KB)


Explorers Club Fellow, ex-NASA Space Station Payload manager/space biologist, Away Teams, Journalist, Lapsed climber, Synaesthete, Na’Vi-Jedi-Freman-Buddhist-mix, ASL, Devon Island and Everest Base Camp veteran, (he/him) 🖖🏻